The invention relates to an actuator, in particular, with an electromechanical drive, and is used, in particular, in a stabilizer for equalizing vehicle movements.
European patent document no. EP 1 821 390 A2 discloses an electric drive for an adjustable stabilizer, and this electric drive comprises a housing, in which a stator is rigidly mounted, and coaxially thereto a rotator and an electronic unit are arranged for the purpose of operating the electric drive. A conducting wire runs out from the stator through a cover of the housing and is formed by at least one fixed bolt element.
German patent document no. DE 10 2008 000 148 A1 proposes a system, comprising at least one electromechanical stabilizer, a rotational speed sensor and/or a rotational angle sensor arrangement and an electrical connection technique. This system has a one-piece housing, in which the electric motor for operating the at least one electromechanical stabilizer is arranged. An add-on component is attached to the stabilizer. In this case the add-on component has a sensor cable harness with an integrated high current cable and a module, which comprises a least one measuring sensor for detecting a rotor bearing of the electric motor or more specifically a rotational angle sensor and/or a rotational speed sensor. The module also comprises the electrical assembly and connection technique for making contact with the connecting cables of the electric motor.
An actuation of the actuator is not provided in the aforementioned solutions. However, such an actuation is useful when the road lane is uneven, so that it would be possible to compress each wheel independently as a function of the unevenness of the road lane in order to be able to achieve high driving comfort with a suitable adjustment of the wheel suspension.
German patent document no. DE 19714565 A1 discloses a stabilizer arrangement that comprises a stabilizer, which is operatively connected to a vehicle body and the wheel control parts, and an actuator, which can be driven by an electric motor and which can provide a torsional moment of the stabilizer that counteracts a rolling moment. In this case a longitudinally adjustable telescopic unit is provided as the actuator; and this telescopic unit comprises a telescopic cylinder for accommodating at least the electric motor and a piston head, which can be arrested in the adjustment mode by a blocking device. In this case a translatory movement of a piston rod, which is axially supported by the head on the piston, can be introduced by way of a gear train by actuating the electric motor; and the result of this translatory movement is a change in the length of the telescopic unit. The telescopic unit comprises the piston head and the piston rod. The piston rod can be arrested in the telescopic cylinder by a blocking device. There is the possibility of actuating the actuator in that in the de-energized state of the actuator the piston is freely movable in the telescopic cylinder. This actuator that can be actuated in the de-energized state has a complicated design configuration and large dimensions.
Japanese patent document no. JP 60-234 171 A describes a design variant for adjusting the tooth flank backlash of two meshing gearwheels. To this end an eccentric axle and an eccentric cylinder rotate about an axial center of the drive axle, so that the gearwheels are always in engagement.
A decoupling of the drive shaft and the output shaft is neither provided nor suggested by this solution.
The object of the present invention is to develop an actuator, in particular having an electromechanical drive, and exhibiting a simple design configuration and an actuation for decoupling the stabilizer halves.
The actuator comprises, in particular, an electromechanical drive and a housing, wherein the driving torque provided by an electric motor is transmitted by a gear train to between two outputs of the actuator that are connected to the two halves of a stabilizer, and the gear train is designed in the form of an eccentric gear train, and the drive shaft of said gear train can be driven with the electric motor, wherein an overall eccentric, on the circumference of which a drive gear having a first outer profile and a second outer profile, which is different from said first outer profile, is arranged, can be driven by the drive shaft; wherein in the operating state of the actuator the axis of the drive gear is arranged in an eccentric manner with respect to the axes of the outputs by the overall eccentric; and, as a result, the first outer profile of the drive gear is operatively connected to an inner profile of a first output; and the second outer profile is operatively connected to a second inner profile of the second output; and that this operative connection can be cancelled by changing the eccentricity of the eccentric; and, thus, both outputs can be rotated freely relative to each other (release).
To this end, the overall eccentric is divided into a drive eccentric, which is connected to the drive shaft, and an eccentric bushing, which is arranged between the drive eccentric and the drive gear, in such a way that during a relative rotation between the drive eccentric and the eccentric bushing, the axis of the drive gear can be adjusted in such a way that it is more or less in alignment with the longitudinal axis of the actuator; and in this position the outer profiles of the drive gear are not operatively connected to the inner profiles of the first and second output.
At least one locking element is provided between the drive eccentric and the eccentric bushing. In the operating state, in which a torque is transmitted to the two outputs, this locking element fixes said drive eccentric and said eccentric bushing with respect to each other in such a way that their eccentricity in a first position adds up; and, thus, the axis of the drive gear lies eccentrically to the axis of the outputs, so that the operative connection to the drives is established and that the locking element for putting into effect the freewheeling releases the connection between the drive eccentric and the eccentric bushing, so that the drive eccentric and the eccentric bushing rotate relative to each other until in a second position their eccentricity is essentially eliminated, so that the axis of the drive gear is placed in essence centrally in relation to the outputs, and the operative connection of the drive gear to the outputs is cancelled. In this second position the drive eccentric and the eccentric bushing are also fixed in position relative to each other preferably by the locking element.
The relative rotation between the drive eccentric and the eccentric bushing in order to change over from the operating state (first position) into the freewheeling state (second position) amounts in essence to 180°. The locking element is preferably magnetically actuable.
This possibility of changing the eccentric position of the drive gear makes it possible to switch easily and quickly from the transmission mode into the freewheeling mode.
A release of both outputs of the actuator is particularly necessary for safety in the event of a power failure and in order to enhance the driving comfort when driving straight ahead in that the copying of the wheel movements is avoided.
Rolling bodies, which transmit the torque, are arranged in an advantageous manner between the outer profiles of the drive gear and the inner profiles of the outputs.
The use of rolling bodies effects in the eccentric gear train a larger force-transmitting surface than is the case with gear teeth that are used in the conventional way, so that it is possible to build smaller and to transmit higher moments and still maintain the same size.
Furthermore, the use of rolling bodies arranged between the profiles makes it possible to achieve a reduction in the friction and the wear, so that the actuator has a long service life even with rapidly varying loads.
In this context the drive gear of the eccentric gear train has a first outer profile, which interacts with a first inner profile of the first output by first rolling bodies. Furthermore, the drive gear is provided with a second outer profile, which is different from the first outer profile, wherein this second outer profile interacts with a second inner profile of the second output by second rolling bodies. When the drive gear rotates, a relative rotation between the first output and the second output is generated due to the different pairings between                a first outer profile/first rolling bodies/first inner profile of the first output, and        a second outer profile/second rolling bodies and second inner profile of the second output.        
As a result, a torque/torsional moment is transmitted to the ends of the stabilizer, so that these stabilizer ends rotate relative to each other and, as a result, the vehicle movements in turn are balanced, because the stabilizer is connected, on the one hand, to the wheel suspension and, on the other hand, to the chassis/vehicle body.
Preferably the first and the second outer profile exhibit different nominal diameters and/or different profile sizes; and the first and second rolling bodies as well as the first and second internal teeth of the outputs are designed to correspond thereto. Furthermore, in order to ensure a slim type of design, the first outer profile and the second outer profile of the drive gear are arranged one after the other along a longitudinal axis of the actuator.
The rolling bodies are designed, in particular, in the form of rollers. In order to avoid running noises, elements (in particular, elastomer rings) are arranged between the drive gear and the first and second rolling bodies; and these elements transmit a prestress force, which acts radially outwards, to the rollers, so that the first and second rolling bodies are constantly prestressed against the corresponding inner profiles of the internal teeth of the two outputs.
The two ends of the roller-shaped rolling bodies are guided in retaining rings, which also exhibit preferably sound-damping properties. Instead of the aforementioned described rolling body teeth, it is also possible to use any conventional gear teeth.
The first output of the eccentric gear train, which is connected to the first stabilizer half, can be designed either in the form of a rotary shaft in a fixed housing; or as an alternative a first output shaft can be formed by the housing. The second output of the eccentric gear train is designed in the form of a second output shaft that can be mounted in a rotatable manner in the housing.
In order to connect to the first stabilizer half, the first output shaft has a first connecting element on the output side; and the second output shaft is provided in an analogous manner with a second connecting element on the output side; and this second connecting element is connected to the second stabilizer half.
According to the invention, the connection between the first output shaft and the first stabilizer half and/or the connection between the second output shaft and the second stabilizer half is/are provided with an overload protection in the form of a slip clutch, which allows the respective connection to slide through, when a predefined moment is exceeded and to catch again upon undershooting this moment. This arrangement ensures that the actuator and the system are protected against overload. A preferred design alternative is to configure the connection to the stabilizer halves by a longitudinal press fit or a transverse press fit. In this case the region of the connection has a layer, in particular a phosphate layer, which ensures the micropositive lock between the respective output shaft and the stabilizer half and transmits the force lock, generated during the press fit, up to the predetermined moment. If the moment is exceeded, the connection rotates between the at least one stabilizer half and the actuator, until the moment lies again in the allowable range.
A measuring arrangement for detecting the torsion between the first output shaft and the first stabilizer half is arranged in an advantageous way between the first output shaft in the form of the housing and the first stabilizer half. In this case the measuring arrangement is designed, in particular, in the form of a torque sensor, the output of which is coupled with a control logic, which controls the motor torque as a function of the torsional moment. In this context it is possible to return a rotation of the outputs of the actuators that has occurred as a result of the overload back into the desired starting position by a counterclockwise rotation. If the torque sensor no longer detects any torsion, then the stabilizer halves may be found once again in the requisite position with respect to the actuator.
The solution according to the invention provides an actuator of a new generation, which provides a larger actuator moment with smaller dimensions than could be achieved to date with conventional types of designs, has a protection against overload and comprises an actuation.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.